This invention relates to a monitor for a nozzle of a sprayer device which is particularly but not exclusively designed for use with field sprayers of a type in which the nozzle is shielded by suitable cover arrangements from the effects of wind and hence is directly not visible to an operative of the sprayer vehicle.
Field sprayers, as is well known, include a suitable vehicle arrangement which carries a tank of the liquid to be sprayed. The vehicle includes booms which extend outwardly to the sides of the vehicle often supported on ground wheels with spray nozzles arranged along the lengths of the booms at spaced positions so as to provide a spray pattern which covers the ground over which the booms move. The liquid is pumped from the container to each of the nozzles. It is of course very important to ensure that each of the nozzles is properly operating since it is essential to control accurately the proper consistent application of a required amount of the liquid over the ground. If one or more of the nozzles fails to operate at all or operates unevenly, one part of the ground will of course therefore not receive its proper dose of the liquid and thus the proper treatment of the crop in that area will be omitted.
Conventional sprayers in which all or most of the nozzles are open to view can be monitored by visual inspection by the operator. Even in sprayers of this type, the operator may overlook a faulty nozzle or one of the nozzles which are not open to view for example those directly behind the container may be faulty and hence may not be visible.
In order to obtain improved spraying efficiency and to enable spraying in higher wind velocities, recent developments have led to various designs of shrouded sprayers for example of the type shown in U.S. Pat. No. 4,646,971 (R. B. Rogers). In sprayers of this type, the spray nozzles are totally hidden from view and hence it is not possible to visually determine whether each of the nozzles is properly operating without the operator leaving the cab and making a direct inspection. Thus one or more of the spray nozzles can become blocked and inoperative during the sprayer operation thus leading to bands of unsprayed or oversprayed areas being formed across the ground.
Various techniques of monitoring the operation of the nozzles are available but it is of course necessary to manufacture a monitoring device which is economically acceptable in the relatively large numbers necessary for monitoring each of the nozzles on a large sprayer which may have up to 60 nozzles in a ninety eight foot width.
Several commercial nozzle monitor devices are available on the marketplace which operate by detecting the volume of fluid flowing to the nozzle so that on a nozzle becoming blocked so as to reduce the flow by a predetermined amount generally the order of twenty percent (20%), the flow monitor detects the change and indicates a fault.
However tip malfunction can exist in many cases with little or no change in flow by a partial blockage of the tip which causes the fluid to flow through only one side of the nozzle thus increasing flow in one area while reducing the flow in another area so that the pattern is faulty. Such faults would not be detected by the flow monitor. Furthermore such faults can be seriously damaging in that modern chemicals in many cases require very accurate levels of application in that an excess amount can cause significant damage to the crop or to the soil.
A device was proposed by Century Engineering around 1975 in which a sensor was attached to the nozzle to detect vibration at that point. Such vibrations were generated by vibration of the boom and by movement of fluid to and through the nozzle. The vibration sensor was however ineffective and was withdrawn from the market at around that time.